sighh....no boost

[4BangerV8Killer]

so yesterday i bought a 92 6/4 for 1500 bucks....checked it out. the only thing is the turbo wont build any pressure at all, not 1 psi.....vacumes fine at -17 off throttle but no boost on throttle. Doesnt bog when i gun it or anything like that. just runs like a crappy 1979 honda would with 50sum hp. I checked the turbo. no oil leaks, shaftplay and comp wheel spins fine. any ideas on what else i could check? today im gonna go ahead and check the ic and try to find a vaccume leak. but are the 14b's prone to having the wastegate stuck open at all?

 

[Wildeclipse2000]

From those pictures you also need to get rid of those aftermarket manifold to turbo bolts, and put the crush gasket washers in there.

 

[4BangerV8Killer]

ya, when the cars running its a loud hissing around the intake mani....ill get the o-rings and stuff and see what happens. but if it were injectors id build boost to the bypass valve at least and i hear nothing blowing off. and i hear no turbo spool.

 

[4BangerV8Killer]

so aside from all that iv said.....what about engine internals? i havent gotten around to doin a compression test yet cause my buddy has mine right now.

 

[Wildeclipse2000]

. but if it were injectors id build boost to the bypass valve at least and i hear nothing blowing off. and i hear no turbo spool.

The only time you will hear anything from the BOV is when you are building boost, and you are not doing that with a leak in the system.

 

[4BangerV8Killer]

yaya i know that but im saying if im not "blowing off" then the major leak must be before the valve? (i.e. intake, turbo, ic.) right?

 

[Wildeclipse2000]

yaya i know that but im saying if im not "blowing off" then the major leak must be before the valve? (i.e. intake, turbo, ic.) right?

Your whole intake path is a pressurized system, and the leak wherever it is in the intake system is acting like a constant BOV, always releaving the pressure from the turbo.

 

[4BangerV8Killer]

true true....i was thinking in terms of a liquid leak not air

 

[4BangerV8Killer]

would the pvc valve alone prevent all boost?

 

[chanley talon]

NO do a boost leak check and then post what you have found. Until then really there is no point in asking anymore questions . We cannot pin point the problem . I would say you have bad orings and the gasket between the manifold and turbo needs replaced and your mani probably has a huge crack underneath. I wouldnt be surprised if the plug on the intake isnt drawing air as under vaccumm and leaking under boost . 9 psi vac means there is a deafenent leak ! It should vac 15-20 at least . If you cant find the problem chunk the turbo and get another one or its a good time to upgrade you can get a good 14b for around 100 dollars.
Has this turbo ever spooled at all for you. If not the turbine wheel could be damaged or the nut on the end could have came loose. If so it would not boost and may apear to be ok . But really it is dead. Try to post some video if you can!

 

[4BangerV8Killer]

**update**

so i did a compression test and it was 150 across and the plugs are fine....but when i go full throttle when its cold....(in the morning) i can hit like 9psi...but dont really feel a power difference and it sounds horrible around 4k and higher

 

[4BangerV8Killer]

i founda crack on the exhaust housing....next to the wastegate flap....i not sure if its enough to prevent the boost...but would it also mess with the vaccum?

 

[janks85]

When it comes to boost leaks, any little leak can cause big boost problems, so their isnt voting out that could be your problem. I'd say fix that leak fix the intake manifold leak, and the injectors then if the problem still persists, do a boost leak test, and if that goes through see if you can get your hands on a cheap 14b and see if its the turbo itself. Your saying the shaft spins free and the wastegate opens and closes tightly, so if theirs no boost leaks (after the intake mani gasket and the housing crack is fixed) id say it has to be something internally with the turbo, our turbo ssytem isnt to complicated so if you rule out boost leaks/blown gaskets theirs pretty much only one other thing that could be the problem..the turbo or the wastegate but you said the arm feels fine.

 

[pikepeaktalon]

Here's a thought. What if you have a severlly clogged cat and the his is comming from the flex housing. I have seen this on a non turbo car so i would think that that would cause a no boost problem and allow the car to run.